1. Field of the Invention
The present invention relates to a pneumatically driven setting tool including a drive-in piston displaceably supported in the guide, driven by a gaseous pressure medium, and having a piston stem, a compression device for providing the gaseous pressure medium for driving the drive-in piston, a storage chamber for storing the pressure medium produced by the compression device, and an expansion chamber adjoining the drive-in piston at a side of the drive piston remote from the piston stem, communicating with the storage chamber, and having an opening connecting the expansion chamber with the drive-in piston.
2. Description of the Prior Art
With setting tools described above, fastening elements are driven in a constructional component as a result of drive-in movement of a setting or drive-in piston. In these pneumatically driven setting tools, the setting or drive-in piston is accelerated by an expandable compressed gas volume produced by a compression device.
U.S. Patent Publication US 2002/0158102 A1 discloses a portable pneumatic setting tool having an integrated compression apparatus. The compression apparatus includes a motor and a compressor arranged in the tool housing. The motor is supplied with electrical energy from a battery releasably secured on the cover of the compression apparatus. The compressed air, which is produced by the compression apparatus is stored in a storage chamber and is fed, upon actuation of an actuation switch, into an expansion chamber located behind the piston which is driven by the expanding compressed air.
A drawback of the setting tool, which is disclosed in the above-mentioned U.S. publication, consists in that the compressor, together with the expansion chamber, occupy a large volume of the tool space.
German Publication DE 37 28 454 A1 discloses a pressure medium-driven percussion tool with a pneumatic drive piston which is supplied with compressed air from a compressor built-in the tool housing. The produced compressed air is stored in one or several storage chambers and, upon actuation of a control valve, drives the drive piston that impacts a fastener or the like. The compressor is driven by electric motor through an eccentric gear.
In the setting tool of DE 37 28 454 A1, a large space volume of the tool is needed for the compressor and the expansion chamber.
Accordingly, an object of the present invention is to provide a setting tool of the type discussed above that would have a small volume.